Oral care and personal health care formulations deliver molecules to the oral cavity that are not only bitter, but also astringent, for example, metal salts have a high degree of astringency and bitterness. One method of determining the level of bitterness and astringency has been through the use of cellular based assays. Buccal cells, such as TR146, have been widely used as screens for pharmaceutical uptake (H. M. Nielsen & M. R. Rassing. Int. J. Pharm. (1999) 185(2): 215-25). This cell line was derived from a squamous cell carcinoma and thus allows for continuous propagation of the cell line. The TR146 cells uptake of molecules has been used previously to determine the biological interaction with the host tissues, even though these cells are significantly different than analogous cells from healthy tissue.
Therefore, there is a need to have a cell-based assay for determining the amount of bioavailable metal ion delivered from an oral care product that uses cells or conditions more closely related to cells in the human body. Meeting such a need will allow for predicting the level of astringency an oral care product would deliver. The TR146 cells also provide a means to gauge the level of astringency in the mouth by monitoring the level of uptake of the targeted molecule. Additionally, the TR146 cells allow for monitoring the amount of soluble Zinc in an oral care formulation